Method for colouring substrates containing cellulose

Abstract

The present invention relates to a process for coloring cellulosic substrates, which comprises substrates to be colored, or precursors thereof, being contacted with at least one treated pigment in particulate form that is at least partially enveloped by at least one cationic copolymer.

1 : A process for coloring cellulosic substrates, which comprises substrates to be colored, or precursors thereof, being contacted with at least one treated pigment in particulate form that is at least partially enveloped by at least one cationic copolymer. 
   
   
       2 : The process according to  claim 1 , wherein cationic copolymers comprise copolymers constructed of at least one nonionic comonomer and at least one comonomer having at least one protonatable nitrogen atom per molecule. 
   
   
       3 : The process according to  claim 1 , wherein substrates to be colored, or precursors thereof, are contacted with at least one treated pigment in particulate form that has been prepared according to a process comprising the steps of:
 a) dispersing at least one pigment in particulate form with at least one nonionic surface-active material,   b) mixing the thus obtainable dispersion of pigment in particulate form and nonionic surface-active material with aqueous medium,   c) addition polymerizing at least one first monomer or addition copolymerization of a first mixture of comonomers in the presence of a mixture according to b) to form water-insoluble polymer or copolymer on the surface of pigment in particulate form,   d) adding at least one second monomer or a second mixture of comonomers and addition polymerization or copolymerization.   
   
   
       4 : The process according to  claim 1 , wherein step d) produces a polymer or copolymer having a glass transition temperature T g  of −30° C. or higher. 
   
   
       5 : The process according to  claim 1 , wherein pigments in particulate form are selected from carbon black, calcium carbonate, kaolin and organic pigments. 
   
   
       6 : The process according to  claim 1 , wherein the first monomer in step c) comprises a vinylaromatic compound or a compound of the general formula I 
     
       
         
         
             
             
         
       
       where 
       R 1  is selected from hydrogen, branched C 1 -C 10 -alkyl or unbranched C 1 -C 10 -alkyl, 
       R 2  is selected from hydrogen, branched C 1 -C 10 -alkyl or unbranched C 1 -C 10 -alkyl, 
       R 3  is selected from branched C 4 -C 10 -alkyl or unbranched C 4 -C 10 -alkyl. 
     
   
   
       7 : The process according to  claim 1 , wherein the first mixture of comonomers comprises a mixture of at least one vinylaromatic compound and at least one compound of the general formula I. 
   
   
       8 : The process according to  claim 1 , wherein R 1  and R 2  are both hydrogen in one compound of the general formula I. 
   
   
       9 : The process according to  claim 1 , wherein the second monomer added is a monomer of the general formula II 
     
       
         
         
             
             
         
       
       where 
       R 4  is selected from hydrogen, branched C 1 -C 10 -alkyl or unbranched C 1 -C 10 -alkyl, 
       R 5  is selected from hydrogen, branched C 1 -C 10 -alkyl or unbranched C 1 -C 10 -alkyl, 
       R 6  is selected from branched C 1 -C 10 -alkyl or unbranched C1-C10-alkyl. 
     
   
   
       10 : The process according to  claim 1 , wherein the second mixture of comonomers comprises at least one monomer of the general formula II. 
   
   
       11 : The process according to  claim 1 , wherein R 4  is hydrogen or methyl and R 5  is hydrogen in one compound of the general formula II. 
   
   
       12 : The process according to  claim 1 , wherein the second mixture of comonomers comprises at least one comonomer selected from vinylaromatic compound and a compound of the general formula I. 
   
   
       13 : The process according to  claim 1 , wherein step d) comprises up to 20% by weight, based on the second mixture of comonomers, of at least one compound of the formula V a or V b 
     
       
         
         
             
             
         
       
       where 
       R 10  to R 12  are the same or different and are each selected from hydrogen, branched C 1 -C 10 -alkyl and unbranched C 1 -C 10 -alkyl, 
       X is selected from hydrogen, glycidyl, protonatable groups having tertiary amino groups and enolizable groups having 1 to 20 carbon atoms. 
     
   
   
       14 : The process according to  claim 1 , wherein cellulosic substrates comprise wood. 
   
   
       15 : The process according to  claim 1 , wherein cellulosic substrates comprise woody or so-called wood-free paper and the paper precursor comprises paper stock. 
   
   
       16 : Colored cellulosic substrates obtainable by a process according to  claim 1 . 
   
   
       17 : Treated pigments in particulate form prepared by
 a) dispersing at least one pigment in particulate form with at least one nonionic surface-active material,   b) mixing the thus obtainable dispersion of pigment in particulate form and nonionic surface-active material with aqueous medium,   c) addition polymerizing at least one first monomer or addition copolymerization of a first mixture of comonomers in the presence of a mixture according to b) to for water-insoluble polymer or copolymer on the surface of pigment in particulate form,   d) adding at least one second monomer or a second mixture of comonomers and addition polymerization or copolymerization,   wherein copolymer or polymer from steps c) and d) is cationic.   
   
   
       18 : A process for preparing treated pigments according to  claim 17 , which comprises
 a) dispersing at least one pigment in particulate for with at least one nonionic surface-active material,   b) mixing the thus obtainable dispersion of pigment in particulate form and nonionic surface-active material with aqueous medium,   c) addition polymerizing at least one first monomer or addition copolymerization of a first mixture of comonomers in the presence of a mixture according to b) to form water-insoluble polymer or copolymer on the surface of pigment in particulate form,   d) adding at least one second monomer or a second mixture of comonomers and addition polymerization or copolymer or copolymerization,   wherein copolymer or polymer from steps c) and d) is cationic.